#MGB Carb Balancing

I had been running on a pair of early HIF4 carbs – AUD616 to test out the benefits of ported distributor advance. They certainly give a more even tickover due to being a more retarded spark. But the engine – just recently – was not running well so thought i would refit the original FZX1001 carbs. There was no difference and the problem later turned out to be a failing fuel pump. I decided not to refit the AUD616 carbs for the time being since i had got the originals all set and balanced.

The carb balancer is basically made up of 2 parts, the nozzle that you hold onto the carb inlet and the reader measures the level of air flow. The reader is a tapered tube, wider end upwards. A small plastic ball “floats” in the tube and it’s height depends on the amount of air flow.

The nozzle, connected to the reader with a rubber pipe is moved from one carb inlet to the other and comparing the difference the ball in the reader “floats”. The tickover is adjusted on each carb until the readings / float height is the same for each carb.